edit README

Author: joel-ling

README.md

@@ -139,9 +139,8 @@ func main() {
 ```
 
 Compare the first word (four bytes) in the output of `Marshal()`
-to the specifications for bit fields in that word
+to the specifications for the first 32 bits of the Internet Header
 in [Section 3.1](https://datatracker.ietf.org/doc/html/rfc791#section-3.1)
-"Internet Header Format"
 of RFC 791 defining the Internet Protocol.
 
 ```